The first spanish land grant awarded in what is now Nueces county was the Casa Blanca land grant. Granted in 1798 by the spanish government to Juan Jose de la Garza Montemayor (1765-1816) and his three sons, Juan Manuel, Jose Perfecto, and Jose Agustin, it was located between Penitas Creek and the Nueces River. Originally called Penitas Grant, it consisted of 70,848 acres, or sixteen sitios of land. The Montemayor family established a ranch near Penitas Creek. Since it was near the site of Casa Blanca Fort, it became known as Casa Blanca Ranch. Under continual attack by indians, the ranch remained in the Montemayor family until 1849, when it was purchased by William Mann (1818-1855). Mann later divided the lands and sold portions to area farmers and ranchers.
Following his death, his heirs sold 22,000 acres to Richard King. Eventually, oil was discovered in Nueces County, and the owners of the former Casa Blanca Land Grant became oil producers. Today, the principal industries on the Casa Blanca lands are oil and gas production, farming, and ranching. Lands included in the grant now lie in the counties of Nueces (44,042 acres) and Jim Wells (26,806 acres).